Orbital space stations presently in the planning stage require an electrical power source with a lifetime of 20 years or more. A high-ranking candidate system having an outstanding weight to energy storage ratio is the flywheel. In addition to energy storage, a flywheel can also be adapted to provide the further function of a control moment gyroscope for maneuvering the spacecraft.
Many different flywheel systems have been devised for energy storage purposes. Similarly, there many other energy storage systems which utilize solar energy.
Some examples of energy storage systems of possible interest are discussed in the following U.S. Pat. Nos. 3,667,012 (Kilgore); 4,131,827 (Larrabee); 4,177,793 (Schultz); 4,204,147 (Larrabee); 4,212,287 (Dougherty et al); 4,314,198 (Rogers); 4,321,478 (Plunkett et al); 4,333,136 (Baker); and 4,412,170 (Roesel, Jr.). The Baker patent discloses a control unit for controlling the power supplied by photo-voltaic solar panel source to a load. Power is coupled to the load or cut off therefrom in response to the panel voltage being greater or less than a predetermined level. The Larrabee patents both disclose power transfer systems which control the power transferred between a solar cell array and a load. In the later patent, a parameter indicative of the power being delivered to the load is sensed and an impedance matching system is adjusted accordingly. In the earlier patent, a DC motor and an AC induction motor are operated in tandem such that the DC motor, which is powered from the solar cell array, acts to reduce the loading on the AC motor. The Dougherty et al patent discloses an isolation integrator wherein a control signal related to the rate of isolation is integrated to determine whether the signal is adequate for operation of a solar collection system. The Schultz patent discloses a solar heating system incorporating a device providing electrical control signal responsive to the rate of flow of "species of radiant energy" through an area. The Rogers patent discloses a solar source for a lighting system which automatically connects and disconnects the lighting system to and from a rechargeable power source. The Plunkett et al patent discloses an auxiliary power supply including a synchronous machine for storing kinetic energy when the load current load does not exceed the normal steady magnitude thereof and for converting kinetic energy into electrical energy to supply the load current requirement in excess of that magnitude. The Kilgore patent discloses a system including a wound rotor and a flywheel provided on a shaft and wherein a cycloconverter is used to provide speed control of the motor. The Roesel Jr. patent discloses a motor-generator system for providing prolonged uninterrupted power to a load.